Aluminum hydroxide gel is a widely used antacid. It possesses many of the properties of an ideal antacid such as acid consuming capacity and non-absorbability. Many effective antacid fluid dosage forms currently marketed utilize aluminum hydroxide gel. However, when aqueous aluminum hydroxide gel is used to produce a dried gel which can be formulated into solid dosage forms, its total antacid reactivity, as well as acid reaction rate, is decreased. Of even greater potential significance, the aging of dried aluminum hydroxide gel at ambient or elevated temperature results in significant losses in antacid reactivity. An antacid preparation which is initially active can become inactive over a relatively short period of time. However, the convenience of a solid antacid dosage form over a fluid dosage form is readily appreciated and makes highly desirable the development of an initially acid reactive dried aluminum hydroxide gel which maintains its acid reactivity for an extended period of time.